1. Field of the Invention
The present invention relates to a fastener, more particularly to a fastener for securing and positioning a container on the deck of a cargo vessel or ship.
2. Description of the Related Art
Generally, when containers are being transported in a cargo vessel or ship, the containers are stacked on the deck of the ship and secured by fasteners in order to prevent undesired movement or toppling down of the stacked containers. FIG. 1 shows a stack of containers 71 secured to deck fittings on a deck 72 of a ship by fasteners 1 of the type shown in FIGS. 2 and 3. The conventional fastener 1 as shown in FIGS. 2 and 3 includes a hollow tubular connector 11, an elastic element 12, a first pull rod 13 and a second pull rod 14.
The hollow tubular connector 11 is formed by a cylindrical wall 112 enclosing an internal cavity 111 and having two opposed ends, a first bore 113 being formed at one of said opposed ends and a threaded second bore 114 being formed at the other one of said opposed ends. A filling hole 115 is formed on the cylindrical wall 112 in communication with the internal cavity 111 for introducing lubricant therein.
As shown in FIGS. 1 and 3, the first pull rod 13 includes a stem 132 having one end extending through the first bore 113 into the cavity 111 and another end adapted to be fastened onto the container 71, and a retaining head 131 attached to the one end of the stem 132 positioned in the cavity 111. The second pull rod 14 has one end extending threadedly through the second bore 114 into the cavity 111, and another end adapted to be tied to deck fittings on the deck of a ship.
The elastic element 12 is received in the cavity 111 of the connector 11 and is disposed around the stem 132 of the first pull rod 13 to exert a biasing force against the retaining head 131.
When the ship pitches and rolls in a stormy sea thus swaying the stacked containers 71, the elastic element 12 utilizes its own elastic restoring force to push against the retaining head 131 of the first pull rod 13 in a direction opposite the pulling direction of the first pull rod 13, thereby providing a tightening tension between the first and the second pull rods 13,14. Thus, no loosening or disengagement of the pull rods 13,14 from the connector 11 occurs in the course of the swaying motion of the ship.
However, while lubricant may be injected into the filling hole 115 to promote smoothness of compression and expansion of the elastic element 12, only liquid lubricants can be used due to the limited size of the filling hole 115. Such limitation in use is certainly a disadvantage.
Furthermore, in order to avoid interference with the smoothness of the sliding movement of the retaining head 131 of the first pull rod 13, the diameter of the internal cavity 111 of the connector 11 must be made slightly larger than the size of the retaining head 131. This will cause a larger gap (space) to be formed between the elastic element 12 and the cylindrical wall 112, which in turn could easily cause distortion and dislocation of the elastic element 12 to occur when the elastic element 12 is being compressed by the retaining head 131. When the fastener 1 is under a considerably large pulling tension, the elastic element 12 can easily deform and fracture, thus leading to ineffective fastening. Since the elastic element 12 is hidden within the connector 11, the condition of compression of the elastic element 12 cannot be viewed. In view of this, failure of the elastic element 12 cannot be observed from the outside, and this could be dangerous.